A Kanban (KAHN-bahn) inventory is an inventory that everyone in the supplying process steps can see… whether with their physical eyes or via some other continuously updated information stream… such as electronic feedback. A “Kanban Card” as it is frequently called is anything that communicates all the interrogatives except “When” to the supplying step or steps: Who, What, Where, Why, How, How much and any other required information. This can be an actual card-stock card, or a standard hourly or daily email form (actually used very successfully in the Pool Cover Company case. See the About us article), or a physical bin that holds the pre-arranged kanban quantity in it. This “bin” is probably the most common type, especially when the commodity being resupplied is physically small.
The “When” interrogative is supplied by the arrival of the Kanban card / bin / signal: “NOW” or at least according to agreed-upon restocking triggers and levels, typically in First-In-First-Out (FIFO) sequence with previously arrived Kanban cards.
Kanban resupply triggers can and are being used to visually control the moment to moment scheduling decisions for multiple, dependant, process sequences by people on the shop floor or in the back office. Managers control the system in the short-term by establishing stocking levels, re-order points, the fixed re-order quantity, storage locations as well as by reducing critical process setup times via Quick Changeover techniques.
Managers can improve the system in the long-term by gradually reducing the number of kanban cards / bins / signals. As you gradually reduce the inventory in the system, you can SEE systemic problems that have previously been hidden. SEEING is half the journey to FIXING.
Kanban is a beautiful tool. Please see Kanban for the Shopfloor in the Client Suggested Reading Library.